The present invention relates to a method and apparatus to fill an automatic transmission with fluid. More particularly, the present invention relates to a fluid filling process occurring while the torque converter of the transmission is being rotated.
Automatic transmissions for vehicles typically require a predetermined quantity of fluid to ensure proper operation. Various fluid filling devices and methods have been devised to fill transmissions with fluid. One method involves pumping a known-quantity of fluid into the recently assembled transmission. This method suffers from inaccuracy possibly resulting in an over-filled or under-filled transmission. Because some of the components within the transmission have already been “wetted” during previous testing, an unknown quantity of fluid is already present in the transmission.
Another method includes weighing each component of the automatic transmission in a dry state and weighing an assembled automatic transmission which has been properly filled. The difference between the weights correlates to the quantity of fluid to be added. Unfortunately, this method may also be subject to undesirable over-filling or under-filling of the transmission based on component weight variation and model mix complexity.
Yet another method involves filling the transmission to a predetermined level. However, at the time of first filling an automatic transmission, unknown quantities of air are trapped within the torque converter and other cavities of the automatic transmission. Therefore, the transmission may be over-filled or under-filled depending on the quantity of trapped air. Based on the variations previously described, it is common practice for the transmission assembly plant to provide the transmission in an under-filled condition to the vehicle assembly plant. At the vehicle assembly plant, the transmission is coupled to a transmission cooler and the vehicle's engine. Once these connections have been made, a final fill or “top off” operation is performed to assure that the automatic transmission has been filled to the proper level. At the vehicle assembly plant, the top off operation is costly and time consuming.
Accordingly, the present invention provides a method and apparatus for properly filling a transmission at the transmission assembly plant. In particular, a method of filling a transmission with fluid is provided including the steps of pumping fluid through the transmission entering at the first port and exiting through the second port, rotating the torque converter to purge trapped air, shifting the transmission, filling the transmission to a desired level and plugging the first and second ports. Through use of the method and apparatus of the present invention, the transmission is placed in a “road ready” condition and will not require additional fluid to be added in a top off operation at the vehicle assembly plant.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.